Christopher Dean (defendant) robbed a bank. He was carrying a gun during the robbery, and the gun accidentally discharged. The United States (plaintiff) charged Dean with violating a federal law that enhanced the criminal punishment if a defendant carried or used a gun in relation to the commission of a violent crime. The mandatory minimum sentence for violating the law was an additional five years in prison. If the gun was brandished, the mandatory minimum increased to seven years. If the gun was discharged, the mandatory minimum increased to ten years. The district court convicted Dean of the robbery and of the gun charge. The district court sentenced Dean to the mandatory minimum of ten years. Dean appealed, arguing that he did not intend to fire the gun and thus the sentence enhancement should not apply. The United States Court of Appeals for the Eleventh Circuit affirmed the conviction. The United States Supreme Court granted certiorari.